Interaction driver–bicyclist on rural roads: Effects of cross-sections and road geometric elements

  • Published: Accident Analysis & Prevention 102, 2017: p 191-201
  • Authors: Bella, F. & Silvestri, M.
  • Date Added: 08 Mar 2018
  • Last Update: 08 Mar 2018
  • Format: html

Objectives:

To analyse the effects that three cross-section configurations of a two-lane rural road and four geometric elements of the road have on driver behaviour, during the interaction with a cyclist.

Methodology:

A two-lane rural road, about 11 km long, was designed and implemented in an advanced-interactive driving simulator. Three different cross-sections (all with the same width, but with and without a bicycle lane and for different widths of bicycle lane) were tested.

Forty participants carried out three driving sessions (one for each road alignment with different cross-section) and were exposed to the condition of bicycle traffic along four geometric elements of the alignment (2 tangents with different lengths, right curve and left curve).

The driving simulator experiments were designed in such a way that, along the sections where the driver–cyclist interactions occurred, the oncoming traffic was absent.

Overall, 468 speed profiles and 468 lateral position profiles were plotted to obtain the descriptive variables of the driver behaviour during the interaction with the cyclist. The influences of cross-sections, geometric elements and bicycle traffic conditions on driver behaviour were evaluated by a multivariate variance analysis.

Key Findings:

  • The interferences of the cyclist on driver’s behaviour depended on the geometric elements.

  • On tangents, the lowest lateral clearances were recorded and no speed reduction was observed, compared to the cyclist absence condition.

  • On the left curve, the higher lateral clearance was recorded, due to the concordant tendencies of the driver to move away from the cyclist and to cut the curve. This determined an excessive and risky displacement of the vehicle to the opposing lane, whose criticality was also emphasized by the high speed adopted by the driver.

  • On the right curve, the lateral clearance was higher than that recorded on the tangents, probably due to the necessity of the driver to perform the demanding manoeuvre of entering the right curve, which also determined a speed reduction compared to the cyclist absence condition.

  • The obtained results provide suggestions for the most efficient cross-section reorganization of existing two-lane rural roads in order to improve the road safety.

Keywords:

Driver behaviour; Bicyclist; Driving simulator; Road safety

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